The processes of multiphoton ionization(MPI)dissociation of 1,3-dibromobenzene was studied at 266 nm. The time of flight mass spectra of 1,3-dibromobenzene were obtained.We measured the percentage of fragment ions to the total ion current and the dependence on laser intensity of the molecule. Based on the experimental results,the multiphoton ionization-fragmentation(MPIF)mechanism of 1,3-dibromobenzene was discussed. The conclusion is that the primary channel is multiphoton dissociation of parent molecule and multiphoton ionization of neutral fragment. Some formation channels of the small fragment cations were analyzed,i.e. C₆H(+,4),C₅H(+,3),C₄H(+,2),C₃H⁺ etc. and most of ion fragments are produced by ion-fragment dissociation staircase.